Many computer users are using their computer systems to communicate with each other in chat sessions. Each user participating in a chat session transmits messages containing text to all other users. The computer system of each chat session participant displays the transmitted messages from other participants on a display screen. In some conventional systems, each user participating in the chat session is represented by a graphical representation (i.e., a character). Examples of a character are graphical representations of a woman or of a man. A user often selects a character that provides an indication of the user's personality. In addition, each character may be capable of exhibiting gestures and expressions that reflect the emotions of the user represented by the character. As used in this context, a "gesture" refers to a character's body pose, and an "expression" refers to a character's facial pose. Some conventional computer systems enable users to select gestures and expressions for characters.
Some conventional computer systems allow more than one user's character to be displayed on a display screen simultaneously. Typically, users can place their characters on different portions of the display screen. It is possible that users at different computer systems place their characters on the same portion of the display screen simultaneously. In this case, the characters are displayed overlapping each other. The user typically is responsible for positioning the character on the display screen so that the character is not displayed overlapping another character.
The text of a message is typically displayed on the display device. Some conventional systems place this text in a window that has a scroll bar. A user can scroll through the text in this window using the scroll bar. Other conventional systems display the text above the characters on the display device. Yet other conventional systems display the text in a "balloon." The text of a message is often displayed in a bounded area with a border, called a "balloon." For example, a balloon may take on the form of an oval. The balloon has a balloon body that contains the text and a balloon tail that indicates which character is "speaking" the text.
In one conventional computer system, when a character speaks, the computer system displays the character on the display screen. The system also adds a balloon for encapsulating the text of the character's speech. Each time that a character speaks, a new balloon appears that encapsulates this text, and this new balloon replaces the previous balloon for that character. In another conventional system, when a character speaks, a balloon is displayed for that character. As additional characters speak, balloons are generated for their text. However, only the tail of the most recently generated balloon is displayed. That is, for each character that speaks, the tail is removed from the balloon last added to the display device, the bodies of previous balloons appearing on the display are scrolled upwards, and a new balloon is added. The body of the new balloon is displayed on the display screen vertically above the character that spoke and below the other balloon bodies. In this conventional system, when a character is moved, its balloon remains in its original place. Therefore, when a character is moved, it may not be possible to determine which text a particular character spoke. Moreover, in this conventional system, users cannot scroll through the balloons. Therefore, when text is scrolled off of the display screen, the user cannot view it later.
The participation of users in chat sessions may be interrupted by the users having to perform other tasks. To enable users to view a "history" of the discussion for the period the user was not participating in the chat session, some computer systems store the text of the conversation. A user can then view the text to review the discussion that the user missed. However, because the text alone often does not indicate the personality, the emotions, or the actions of a user, a history containing only the text may be inadequate in aiding a user to gain a complete picture of the chat session. In some conventional computer systems, the history provides a graphical representation of a course of events. In particular, one computer system provides a history of the actions performed by an application program by displaying graphical representations of a display screen for instances in time during the execution of the application program. For example, the history provides a graphical representation of the display screen prior to an action performed by the application program, and the history shows another graphical representation of the display screen just after the action was performed by the application program. However, this history provides the output of only a single application program executing at a single computer system.